1. Field of the Invention
The present invention relates to parallel charge signal delivery system useful for communications equipment, signal processor or the like, and a filtering AD converter using the same.
2. Prior Art
As a result of the development of the digital technology, the digital modulation method such as CMDA (Code Division Multiple Access) has rapidly come into wide use; however, the advanced function level required for the system if gradually attaining such a high level that can hardly realized by a method using the digital processing which has been used up to now in terms of system size or power consumption, and more particularly, this problem has already became obvious in the application such as mobile terminal restricted by the power supply.
As an approach to resolve these problems, novel methods have been developed, such as described in the TOKKAIHEI 6-164320, wherein the analog processing is introduced in order to slough off the inefficient power consumption inherent in the conventional digital signal processing.
However, in general, when these are to be realized by a conventional analog signal processing method, the matching problem of devices composing the circuit is extremely important, constituting a serious restrictive condition for the enlargement of the system scale and the minimization of the integrated circuit.
As new solutions to resolve problems inherent in the analog signal processing method as mentioned before, the U.S. Pat. No. 5,539,404 and U.S. Pat. No. 5,537,115 propose signal processing methods using charge transfer devices. These methods are innovative wherein input charge signals are all processed in the charge domain and the system accuracy is determined independently of the circuit manufacturing error. Then, they are considered to consume less power than conventional analog signal processing methods, because they need, in principle, no active device. On the contrary, as these methods consist in forming the output by processing directly input charge signals, they require an exclusive signal duplication technology for using a single input signal to a large number of operations.
For the detail of this technology, please refer to the journal in English published by the Society of Electronic Information Communication (VOL. E79-A, No. 2, February 1996, pp 217-223) of an Incorporated Foundation.
As an example of this, the applicant of the present invention has proposed a method, in the Application Japanese Patent Application Laid Open No Hei 8-174266, comprising the steps of digitizing once the input charge signal and duplicating the charge signal by a plurality of DA converters receiving reference charge signal from a common reference charge signal generator; however, in this case, the degree of parallelism of the whole is restricted by the number of reference charge signal which can be supplied within the unit time and the degree of system parallelism can not be determined as desired to constitute a serious restrictive condition for the enlargement of the system scale.
Moreover, this method has disadvantageous composition in terms of operation time or power consumption, since essentially unnecessary DA and AD conversion are required for the signal duplication.
It is an object of the present invention to propose a data supply method for executing an accurate operation by a number of operation devices taking a single signal as input and also to propose the composition of an unit having both the filter function and the AD converter function, using this method.